Meters serve important functions in everyday commerce and industry. It is often essential to know what quantity of a substance has been transferred from one place to another. For example, residential water meters indicate how much water has been transferred into a residence, while commercial gasoline pump meters indicate how much gasoline has been transferred into a vehicle. Two important commercial liquid fuels that must be metered in a great number of commercial and industrial contexts include liquid propane gas (LPG) and petroleum and petroleum products and derivatives such as gasoline, diesel, fuel oil, etc.
Unfortunately, these fluids, and especially LPG, pose special handling problems and known metering devices to date for these chemicals have been ineffective and prone to wear and breakage. LPG in particular, for example, is a pressurized material that vaporizes easily when the applied pressure is decreased. Moreover, LPG has very little lubricity, so that it easily escapes past seals and provides little lubrication to the interface between seals and other parts such as shafts. The wear due to lack of lubricity leads to even greater leakage past the seals as the problem compounds itself. The end result is at best inaccuracy and at worst a breakdown of the metering system
Although metering system seals, such as between a metering chamber and a register or indicator, are mechanically relatively simple to replace, there are often other considerations that make replacement costly and time consuming. For example, some types of usage scenarios require that the meter be calibrated, verified, and closed by a government agency or entity. Failure of a meter seal in such a scenario requires reopening of the meter, often necessitating that the calibration, verification and closing process be repeated. This often entails delay while waiting for the necessary government officials to travel to the relevant location and perform the needed review. Thus, it is desirable to replace the current breakage prone seals with a system that presents fewer maintenance challenges and allows greater utility of the meter system.